Goal

• Allow the Manila CSI Driver to resize PVs created with it
• The CSI driver has this capability since kubernetes version 1.23 [1]

Why is this important?

A volume is provisioned with a pre-defined size. As application needs change, it may have to be resized to accommodate more data. It's desirable to resize the volume with minimal to no downtime to the application. NAS storage offers a unique elasticity that customers expect - and it requires no downtime. OpenStack Manila provides NAS Shared File Systems as PVs to OpenShift. Volume extensions are supported across all Manila storage backends

Not having the capability to use OpenShift native APIs to extend volumes is a deficiency in functionality as well as the OpenShift User Experience. To work around this limitation,  users would have to access the volume via Manila API to resize the volume. However, doing so would mean that the size in the PVC will not match the actual PV; and the size change isn't accounted for in OpenShift quotas. 

Scenarios

1. User creates a PVC

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pvc-manila
spec:
  accessModes: 
    - ReadWriteMany
  resources:
    requests:
      storage: 10Gi
  storageClassName: csi-manila-gold  

2. User extends the PVC

oc edit pvc manila-pvc

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pvc-manila
spec:
  accessModes: 
    - ReadWriteMany
  resources:
    requests:
      storage: 15Gi
  storageClassName: csi-manila-gold  

Acceptance Criteria

• CI - MUST be running successfully with tests automated
  • Existing e2e tests to test volume extension would suffice:

                storageframework.CapControllerExpansion: true
                storageframework.CapOnlineExpansion:     true

• Release Technical Enablement
• Documentation updates

Dependencies (internal and external)

1. None

 [1] https://github.com/kubernetes/cloud-provider-openstack/commit/291d04bdf9064f1003db04daf4a38203303a537b